California Golden Trout

Oncorhynchus mykiss aguabonita

A California Golden Trout from a small high Sierra stream

Introduction

The California Golden Trout is often cited as being the most beautiful
of the salmonids. These fish are native to the upper South Fork of the
Kern River and Golden Trout Creek in the southern Sierra-Nevada Mountains
of California and were historically found in about 450 miles of stream
habitat (Trout Unlimited 2007). Due to its beauty and popularity with
anglers the California golden trout has been widely stocked outside of
its native range, especially in the high lakes of the Sierra and Rocky
Mountain Ranges. The broodstock used for stocking golden trout outside
their native range is slightly hybridized with hatchery rainbow trout,
but still retains the appearance of the golden trout.

Life History Information

The habitat available within the native range of the California golden
trout consists of small high altitude streams, and as such these fish
only exhibit a stream resident life history type. The typical size of
the home range for adult golden trout is between 55 and 165 feet of stream
habitat, although ranges of up 1800 (~0.3 mile) have been observed (Matthews
1996). These golden trout prefer undercut banks or areas with sedge, although
they are also associated with several other types of habitat as well.
California golden trout are spring spawning fish, like other the subspecies
of rainbow trout and typically spawn during mid-May after runoff has subsided
and water temperatures have warmed up (Knapp and Vredenburg 1996). The
preferred habitat for California golden trout is wider stream reaches
that are typically associated with cattle grazing. Knapp et al. (1996)
showed that California golden trout used smaller gravel, shallower areas
and dig shallower nests than other salmonids.

Status

Even though this trout is the official state fish of California, poor
management has put them at a serious risk of extinction. As the California
golden trout have long been isolated from contact with other species of
trout, they are greatly impacted by the introduction of non-native fish.
Introduced brook trout compete with them for food, brown trout prey on
them and rainbow trout hybridize with them, leading to a loss of their
genetic integrity. Cordes et al. (2006) showed that hybridization with
introduced rainbow trout threatens the genetic integrity of California
golden trout across their entire native range. Although the degree of
hybridization varies from population to population, it is believed that
the only completely pure population occurs in about a three mile stretch
of Volcano Creek (Moyle et al. 2008).

The introduction of non-native fish is perhaps the greatest threat to
the continued existence of golden trout, but degraded habitat conditions
also pose a serious problem as well. In an effort to address these issues
Congress designated the 306,000 acre Golden Trout Wilderness area in 1978,
but grazing practices and recreational use continue to degrade the habitat
to this day. Livestock grazing has occurred in the California golden trout's
native range since the 1800's with cattle and sheep being the primary
animals that are raised in the area. Knapp and Mathews (1996) showed that
ungrazed stream reaches in the Golden Trout Wilderness had significantly
higher densities and biomasses of trout when those that were grazed. Ungrazed
areas also had great canopy shading, stream depth and smaller stream widths
than what was found in grazed areas. It will be important that these issues
are properly addressed, so that the world will continue to be graced by
the beauty of the California golden trout.

Description

The California golden trout is perhaps the most brilliantly colored salmonid.
The backs of these fish can range from bronze or copper color to dark
olive, which transitions to a golden yellow color that becomes quite intense
below the lateral line. The belly in most individuals is a bright orange
color, but the intensity of this coloring varies with age, size and maturity
of the fish. Dark purple parr marks are present into adulthood in California
golden trout within their native range, but have been known to fade on
large lake dwelling fish stocked outside their native range. There is
a red or pink stripe along the lateral and the same coloration is found
on the gill plates. The fins are an orange or yellow color and the dorsal,
anal and pelvic fins have a dark border outlined with white, or orange
on the dorsal fin. The spots are round, large to moderate in size and
are isolated above the lateral line and on the dorsal and caudal fins.
Often times the spots are concentrated near the tail on the caudal peduncle,
as is also common in many subspecies of cutthroat. This coupled with the
fact that these fish also typically have orange cutthroat marks led to
a great deal of confusion to whether golden trout should be aligned with
cutthroat or rainbow trout. It was only with an improvement in techniques
for analyzing the genetic makeup of these fish that it became evident
that they are of the rainbow trout lineage.

Stream Resident Form

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Native Range

A map of the native range of the California Golden trout. Data Source: Behnke (2002).